Water is a prime natural resource and precious national asset and one of the chief constituents of the environment. The chemical characteristics play a key role in terms of ecological and economic perspectives in the river water. The characterization and evaluation of river water quality in the Karmanasha River is necessary due to its immense importance in the livelihood of the people in the core urban areas of Kathmandu valley, Nepal. In this study, the surface water samples were collected from 16 sites with a 0.5 km interval to characterize and evaluate the water quality mainly from the perspective of its irrigational usage. The assessment was carried out by applying electrical conductivity (EC), sodium percentage (Na%), sodium adsorption ratio (SAR), permeability index (PI), Kelly’s ratio (KR), magnesium adsorption ratio (MAR), cation ratio of soil structural stability (CROSS), Wilcox diagram and water quality index (WQI) including the general hydrochemistry. The general hydrochemistry of river water indicates slightly alkaline in nature with mean pH value 8.07, and the dominance order of major ions follows the pattern of Ca2+>Mg2+>Na+>K+ for cations, and HCO3->Cl->NO3- for anions. Furthermore, the results revealed that the water is safe for irrigation purposes based on EC, Na%, SAR, KR, MAR, CROSS, and Wilcox diagram. The results also specified that no severe degradation in water, however, the low DO, and high BOD and COD values than that of the standard value prescribed by Nepal Drinking Water Quality Standard, signify the anthropogenic signature in the river water. This study provides the baseline information about the WQI and suitability of irrigation water quality, and further in-depth studies are required at spatiotemporal levels to get in-depth insights about the ecological health of the river.

The effect of invasive species on biodiversity is a major issue of world. This study was conducted at the Shivapuri Nagarjun National Park. This study assessed the invasive species status factor associated with it and their impact on seedling and sapling of trees. Modified Whittaker Nested sampling stratifies was adopted for vegetation sampling. A total of 15 plots were taken with 195 subplots between 1409 m to 2140 m. altitudinal ranges. A total of 32 tree species and nine invasive species were recorded from the studied sites. The pine forest was having significantly (W = 3, p = 0.03) more coverage of invasive species than mixed forest, the coverage of invasive species was also significantly (W = 50, p = 0.009) more with more invasive species than plot with single invasive types. Beside this coverage was also affected by canopy cover, trampling and altitude but not significantly different. The invasive species have impact on numbers of seedling, sapling and their diversity species coverage. We recommend removing these invasive species.

Hydropower plants are a quintessential source of clean and economical energy, serving as the primary preference for renewable energy technologies for many governments owing to their unparalleled ability to deliver dependable baseload power with negligible fluctuation. However, despite their numerous benefits, the construction and operation of these plants pose a significant threat to the population living in the river basin and the equipment involved. The damage caused by flooding can have devastating and long-lasting impacts on the area, leading to severe economic losses and a prolonged period of recovery. In the case of the Dordi Rural Municipality, a study was carried out, which revealed that the Upper Dordi Hydropower Plant Headwork and Super Dordi Hydropower Plant inlet were ravaged by a ruinous flood, which resulted in the loss of twenty million equipment and eleven workers die. The cause of the flood was attributed to the upstream landslide blockage, which eventually led to the sudden bursting of the blockage and subsequent flooding. While the compensation of the workers was provided by the District Administration Office, Lamjung, and Dordi Rural Municipality through their incurrence policy, the study underscores the urgent need to establish a highly frequent flood warning system to alert the hydropower station and the local community. Additionally, the scouring and deposition process in the river channel was observed in detail, and the data analysis indicates no significant relationship between discharge and rainfall, emphasizing the importance of proactive measures to prevent future flooding events.